Search Results (98)

In recent years, the majority of countries have focused on the development of earth-penetrating weapons and the construction of deep underground fortifications. It is therefore necessary to assess the damage to underground structures under the attacks of earth-penetrating weapons. In this paper, fluid–solid coupling and restarting methods are used to simulate the damage processes of a granite chamber subjected to the combined action of penetration and explosion with the commercial software of LS-DYNA R11. The applicability of the penetration model and the blasting model is verified by the previous penetration and blasting tests. The verified models are used to simulate the complete process of the underground granite chamber attacked by the earth-penetrating weapons. Based on peak particle velocity (PPV) damage criteria, the numerical results show that the hypervelocity impact of the earth penetrating weapons only causes local damage to the granite rock mass, and more serious damage is caused by the subsequent explosion. During the subsequent explosion, part of the detonation products and energy can escape along the penetration trajectory with the blast loading, resulting in the attenuation of blast stress waves. Subsequently, the relationship between the overlay thickness and the vibration attenuation in granite is also studied, which provides a fast method to determine the threshold damage level for an underground chamber to collapse under the attacks of earth-penetrating weapons. Full article

The Jurassic Tamulangou Formation in the Hongqi Depression has favorable hydrocarbon generation conditions and great resource potential. This study systematically analyzes the geochemical characteristics and thermal evolution history of the source rocks using data from multiple key wells. The dark mudstone of the Tamulangou Formation has a thickness ranging from 50 to 200 m, with an average total organic carbon (TOC) content of 0.14–2.91%, an average chloroform bitumen “A” content of 0.168%, and an average hydrocarbon generation potential of 0.13–3.71 mg/g. The organic matter is primarily Type II and Type III kerogen, with an average vitrinite reflectance of 0.71–1.36%, indicating that the source rocks have generally reached the mature hydrocarbon generation stage and are classified as medium-quality source rocks. Thermal history simulation results show that the source rocks have undergone two major thermal evolution stages: a rapid heating phase from the Late Jurassic to Early Cretaceous and a slow cooling phase from the Late Cretaceous to the present. There are differences in the thermal evolution history of different parts of the Hongqi Depression. In the southern part, the Tamulangou Formation entered the hydrocarbon generation threshold at 138 Ma, reached the hydrocarbon generation peak at approximately 119 Ma, and is currently in a highly mature hydrocarbon generation stage. In contrast, the central part entered the hydrocarbon generation threshold at 128 Ma, reached a moderately mature stage around 74 Ma, and has remained at this stage to the present. Thermal history simulations indicate that the Hongqi Depression reached its maximum paleotemperature at 100 Ma in the Late Early Cretaceous. The temperature evolution pattern is characterized by an initial increase followed by a gradual decrease. During the Late Jurassic to Early Cretaceous, the Hongqi Depression experienced significant fault-controlled subsidence and sedimentation, with a maximum sedimentation rate of 340 m/Ma, accompanied by intense volcanic activity that created a high-temperature geothermal gradient of 40–65 °C/km, with paleotemperatures exceeding 140 °C and a heating rate of 1.38–2.02 °C/Ma. This thermal background is consistent with the relatively high thermal regime observed in northern Chinese basins during the Late Early Cretaceous. Subsequently, the basin underwent uplift and cooling, reducing subsidence and gradually lowering formation temperatures. Full article

Taking the coastal area of Binhai County, Jiangsu Province, as an example, this study first investigated the basic natural geography and the regional geological and hydrogeological conditions of the study area, and then carried out in-depth geophysical prospecting, hydrogeological tests, geothermal temperature monitoring, hydrochemistry and isotope analyses, and other studies based on the results to comprehensively and systematically reveal the genesis mechanism of the geothermal water resources of this coastal area from multiple perspectives. The results showed the following: the geothermal water in this area mainly comes from atmospheric precipitation; the deep east–northwest interlaced fracture is the recharge and transportation channel; the Cambrian–Ordovician carbonate rock layer, enriched by the development of cavernous fissures, forms the thermal storage layer; the underground heat mainly comes from the upward heat flow along the deep fracture and the natural warming of the strata; and the thermal reservoir cover comprises Paleozoic and Mesozoic clastic rocks that have a high mud content and form a thick layer. The genesis mode of this area is as follows: the atmospheric precipitation infiltrates and is recharged through the exposed alpine carbonate fissures in the Lianyungang area, and then it is transported to the south along the large deep fracture under the action of a high hydraulic pressure head; meanwhile, it is heated by the heat flow in the deep part of the fracture and water–rock interactions with the strata occur. Geothermal water with a calculated thermal storage temperature of 83.6 °C is formed at a depth of 2.9 km, which is blocked by the intersection of the northeast and northwest fractures to form a stagnant zone in the coastal area. Full article

Fractures and voids are widely distributed in slope rock masses. These defects promote crack initiation and propagation, ultimately leading to rock mass failure. Investigating their damage evolution mechanisms and strength characteristics is of significant importance for slope hazard prevention. A numerical simulation study of Brazilian splitting tests on disk samples containing prefabricated holes and fractures was conducted using the Finite Element Method with Cohesive Zone Modeling (FEM-CZM) in ABAQUS by embedding zero-thickness cohesive elements within the finite element model. This 2021 study analyzed the effects of fracture angle and length on tensile strength and crack propagation characteristics. The results revealed that when the fracture angle is small, cracks initiate near the fracture and propagate and intersect radially as the load increases, ultimately leading to specimen failure, with the crack coalescence pattern exhibiting local closure. As the fracture angle increases, the initiation location of the crack shifts. With an increase in fracture length, the crack initiation position may transfer to other parts of the fracture or near the hole, and longer fractures may result in more complex coalescence patterns and local closure phenomena. During the tensile and stable failure stages, the load–displacement curves of samples with different fracture angles and lengths exhibit similar trends. However, the fracture angle has a notable impact on the curve during the shear failure stage, while the fracture length significantly affects the peak value of the curve. Furthermore, as displacement increases, the proportion of tensile failure undergoes a process of rapid decline, slow rise, and then rapid decline again before stabilizing, with the fracture angle having a significant influence on the proportion of tensile failure. Lastly, as the fracture angle and length increase, the number of damaged cohesive elements shows an upward trend. This study provides novel perspectives on the tensile behavior of fractured rock masses through the FEM-CZM approach, contributing to a fundamental understanding of the strength characteristics and crack initiation mechanism of rocks under tensile loading conditions. Full article

The Carboniferous reservoirs in the northwestern margin of the Junggar Basin exhibit complex lithological assemblages, primarily composed of siltstone, sandy conglomerate, tuff, and igneous rocks. These reservoirs are rich in oil and gas resources but have entered the middle to late stages of development. The reservoir spaces in the Carboniferous system are mainly composed of pores and fractures, resulting in a complex storage system. To provide effective strategies for stabilizing and enhancing production during the middle to late development stages, it is essential to establish a dual-porosity and dual-permeability model based on a clear understanding of lithological distribution patterns. This will facilitate the identification of favorable zones and the proposal of effective development strategies through numerical simulation. The present study systematically identified the lithology of the study area through microscopic lithological identification combined with logging data, conducted reservoir matrix property research under facies constraints, and established a three-dimensional geological model of lithology and physical properties. To more reasonably study the reservoir development process and establish an optimal development plan, a machine learning model for fracture density was trained using imaging logging interpretation results and conventional logging curve data. The model was then utilized to calculate single-well fracture density. Finally, a fracture model of the study area was established based on the collaborative constraints of fracture density and three-dimensional seismic attributes. Using the results of the established dual-porosity and dual-permeability model and production data, reservoir production evaluation and residual oil distribution research were conducted. The results indicate that the southwestern part of the study area features thick sandy conglomerate reservoirs with good physical properties, continuous lateral distribution, and high residual oil content, making it a dominant area favorable for horizontal well development and production. Additionally, reservoir numerical simulation was employed to study enhanced production development strategies. It is recommended to adopt gas–water alternating injection to improve production, with the optimal gas–water injection ratio of 4:1 yielding the maximum reservoir recovery factor. This study provides theoretical and technical support for the development of complex lithologic buried-hill reservoirs in the Carboniferous system of the western margin of the Junggar Basin. Full article

Taking the Guojiawan coal mine in the Shenfu Mining Area as a case study, five evaluation factors (aquifer thickness, brittle–plastic rock thickness ratio, core recovery rate, number of sandstone–mudstone interbeds, and fractal dimension of the faults) were selected as indicators to evaluate the water richness of the sandstone aquifer in the roof strata of the main coal seam. Accordingly, the weights of the water richness evaluation indicators, derived using the criteria importance through intercriteria correlation (CRITIC) evaluation method, were integrated with the computational procedures of the technique for order of preference by similarity to ideal solution (TOPSIS) evaluation method. The indicator weights and evaluation approaches were combined through different fusion strategies. Finally, based on the water richness zoning results for the study area, the advantages and disadvantages of the two fusion approaches, C-TOPSIS-a and C-TOPSIS-b, were compared. Comprehensive analysis was conducted to evaluate the rationality of the water richness zoning. The C-TOPSIS-b evaluation method achieved the optimal evaluation outcome. The water richness was classified into five grades: weak, relatively weak, moderate, relatively strong, and strong. Among these, the regions with weak to relatively weak, moderate, and strong to relatively strong water richness are primarily in the northern, central, southern, and southwestern parts, respectively. Full article

Deep coal mining is essential for energy use and sustainable development. In a situation where coal–rock–gas dynamic disasters are prone to occur in coal seam variation areas affected by different degrees of roof angle during deep coal seam mining, a disaster energy equation considering the influence of roof elastic energy is established, and the disaster energy criterion considering the influence of roof elastic energy is derived and introduced into COMSOL6.1 software for numerical simulation. The results show that, compared with the simple change of coal thickness and coal strength, the stress concentration degree of a thick coal belt with small structure is higher, and the maximum horizontal stress can reach 47.6 MPa. There is a short rise area of gas pressure in front of the working face, and the maximum gas pressure reaches 0.82 MPa. The plastic deformation of the coal body in a small-structure thick coal belt is the largest, and the maximum value is 18.04 m³. The simulated elastic energy of rock mass is about one third of that of coal mass, and the influence of the elastic energy of roof rock on a disaster cannot be ignored. When the coal seam is excavated from thin to thick with a small-structural thick coal belt, the peak value of the energy criterion in front of the excavation face is the largest, and the maximum value is 1.42, indicating that a dynamic disaster can occur and the harm degree will be the greatest. It is easy to cause a coal and gas outburst accident when the excavation face enters a soft coal seam from a hard coal seam and a small-structural thick coal belt from a thin coal belt. Practice shows that holistic prevention and control measures based on high-pressure water jet slit drilling technology make it possible to increase the average pure volume of gas extracted from the drilled holes by 4.5 times, and the stress peak is shifted to the deeper part of the coal wall. At the same time, the use of encrypted drilling in local small tectonic thick coal zones can effectively attenuate the concentrated stress in the coal seam and reduce the expansion energy of gas. This study enriches our understanding of the mechanism of coal–rock–gas dynamic disaster, provides methods and a basis for the prevention and control of dynamic disaster in deep coal seam variation areas, and promotes the sustainable development of energy. Full article

The issue of slope stability in earthquakes has become increasingly prominent with the construction of many infrastructure projects such as highways, bridges, and tunnels. To explore the dynamic response characteristics of bedding rock slopes in an earthquake, the three-dimensional dynamic finite-difference method (TDD-FDM) in this study is used to establish simplified rock slope models, taking a bedding rock slope with alternatively distributed soft and hard rock layers in Yunnan, China as a prototype. The dynamic response mechanism of layered rock slopes containing different thicknesses, locations, and quantities of soft rock layers was studied under different excitation directions of seismic waves. The main findings are that the propagation of seismic waves at different rock layer structures has directionality, which causes the strongest seismic response to be all located in the upper or middle parts of the slope; the influence of rock structures on seismic response in layered rock slopes is in the order of thickness > quantity > location; the acceleration amplification effect of a slope under multi-directional seismic wave excitation exhibits the phenomena of differential amplification and coupling amplification; and the acceleration amplification factors of a slope with increasing peak ground acceleration from 0.05 g to 0.20 g show two trends: increasing–decreasing and continuous increasing. The findings of this study can be a reference for studying the dynamic response of rock slopes in strong earthquakes. Full article

The Kalatag mineralization belt is an important metallogenic belt of polymetallic mineral deposits in the northern part of eastern Tianshan, and its age and tectonic setting are still controversial. We identified a set of Devonian volcanic rocks hosted in the Early Palaeozoic package of dominantly marine sediments with a small amount of terrestrial rocks. This study presents petrological, U–Pb geochronology, and geochemical data for the volcanic rocks. The ages of the rhyolite (407.2 ± 1.9 Ma) and basaltic andesite (380.4 ± 2.8 Ma) suggests that the Kalatag belt is a Devonian volcanic succession. These rocks consist mainly of marine calc–alkaline lava, tuff, pyroclastic rocks, and minor terrestrial basaltic andesite. The lavas are characterized by the enrichment of light rare earth elements and strongly depleted in Nb and Ta, typical of island arc magmatic rocks. The volcanic rocks probably originated from the partial melting of the mafic lower crust which was modified by subducted slab-related fluids. During their ascent through the crust, these volcanic rocks underwent variable extents of fractional crystallization (rhyolites) and crustal contamination (basaltic andesites). Combined with the results of previous studies, we suggest that the Devonian rocks formed in an island arc related to the northward subduction of the Northern Tianshan Ocean with a crustal thickness of ~35–40 km. Full article

The Kraaipan and Amalia greenstone belts in South Africa occur in the western part of the Kaapvaal Craton. The two belts stretch discontinuously in an approximately north–south orientation over a distance of about 250 km from southern Botswana in the north to the Vaal River near Christiana in the south and are separated by a distance of about 90 km. Gold mineralization is hosted in banded iron formation at both the Kalahari Goldridge deposit (Kalgold) in the Kraaipan greenstone belt in the north and the Amalia deposit in the Amalia greenstone belt in the south, with the mineralization associated with quartz–carbonate veins. The footwalls of these deposits are generally composed of mafic volcanic schist and the hanging walls consisting of graywackes, schist and shale units. The Kalgold and Amalia gold deposits show some variation in the redox condition of the mineralizing system and fluid chemistry. The ore mineral assemblage is characterized by magnetite–pyrrhotite–pyrite at Kalgold, which is indicative of reducing conditions, and a magnetite–hematite–pyrite assemblage at Amalia that suggests a relatively oxidizing environment. Average mineralizing temperatures determined from chlorite geothermometry were relatively higher at the Kalahari Goldridge deposit ranging from 350 to 400 °C compared to the slightly cooler range of 330 to 390 °C at Amalia. The composition of the fluids derived from fluid inclusions is indicative of low salinity H₂O--CO₂±CH₄-rich fluids at Kalgold against relatively H₂O-CO₂-rich fluids at Amalia. Evidence from strontium–carbon–oxygen isotopic ratios from carbonates suggests that differences in redox conditions in the deposits could be attributed to different flow pathways by an evolving fluid from a common source (with minimum ⁸⁷Sr/⁸⁶Sr = 0.70354) to the sites of gold deposition, with a significant ore fluid interaction with a thick sequence of carbonaceous meta-pelitic rock units at the Kalahari Goldridge deposit that is absent in the Amalia deposit. Full article

Cambrian subsalt dolomite is an important strategic area for natural gas exploration in the Tarim Basin. The gypsum-salt rocks, argillaceous mudstone and argillaceous dolomite strata developed in large areas of the Middle Cambrian can be used as good caprocks. The sealing ability and favorable area distribution of the Middle Cambrian caprock in the Tarim Basin are studied through the lithofacies paleogeography and microscopic evaluation of the Middle Cambrian strata in this paper. Based on the 2D seismic interpretation covering the entire basin, combined with data from drilling, outcrops, well logging, core samples and thin sections, the sedimentary characteristics and lithofacies paleogeography of the Middle Cambrian were studied and then the thickness of the Middle Cambrian gypsum-salt rocks, gypsiferous mudstone and gypsiferous dolomite was analyzed in the Tarim Basin. Studies suggest that the Middle Cambrian is primarily characterized by the development of restricted-platform facies. In the Awati Depression, the northern part of the Tazhong Uplift, the southern part of the Manxi Low Uplift, and the central and northern parts of the Bachu Uplift, the thickness of the gypsum-salt rock strata is relatively large. Moreover, centered on the northern part of the Bachu Uplift, the thickness of the gypsum-salt rocks decreases irregularly towards the periphery, forming a circumferential distribution. To investigate the sealing ability of caprocks, 64 core samples from four wells were examined under a microscope, and physical parameters as well as breakthrough-pressure tests were conducted. By establishing correlations between various parameters, the sealing ability of different rock types in the Cambrian formation within the study area was quantitatively assessed. The research suggests that gypsum-salt rocks exhibit superior sealing ability compared to gypsiferous mudstone and gypsiferous dolomite, but factors such as faults and geological conditions of gypsum can influence the sealing performance of caprocks. According to both micro- and macro-scale evaluations of the Cambrian strata in the study area, along with constraints imposed by actual drilling exploration results, a comprehensive evaluation method for assessing caprock sealing ability has been established. The results suggest that the Awat Depression, the western and southern parts of the Manxi Low Uplift, the northern and western parts of the Tazhong Uplift, and the central part of the Tabei Uplift are favorable areas for the development of caprocks. Full article

The Yamal-Nenets Autonomous District, especially the Yamal Peninsula located in the permafrost zone, stores Russia’s largest oil and gas resources. However, development in the area is challenging because of its harsh climate and engineering–geological features. Drilling in oil and gas fields in permafrost faces problems that are fraught with serious accident risks: soil heaving leading to the collapse of wellheads and hole walls, deformation and breakage of casing strings, gas seeps or explosive emissions, etc. In this respect, knowledge of the permafrost’s structure is indispensable to ensure safe geological exploration and petroleum production in high-latitude regions. The extent and structure of permafrost in West Siberia, especially in its northern part (Yamal and Gydan Peninsulas), remain poorly studied. More insights into the permafrost’s structure have been obtained by a precise sTEM survey in the northern Yamal Peninsula. The sTEM soundings were performed in a large oil and gas field where permafrost is subject to natural and anthropogenic impacts, and its degradation, with freezing–thawing fluctuations and frost deformation, poses risks to exploration and development operations, as well as to production infrastructure. The results show that permafrost in the western part of the Yamal geocryological province is continuous laterally but encloses subriver and sublake unfrozen zones (taliks) and lenses of saline liquid material (cryopegs). The total thickness of perennially frozen rocks is 200 m. The rocks below 200 m have negative temperatures but are free from pore ice. Conductive features (<10 Ohm﮲m) traceable to the permafrost base may represent faults that act as pathways for water and gas fluids and, thus, can cause a geohazard in the oil and gas fields (explosion of frost mounds, gas blow during shallow drilling, etc.). Full article

Low-maturity shale oil predominates in shale oil resources. China’s onshore shale oil, particularly the Cretaceous Nenjiang Formation in the Songliao Basin, holds significant potential for low-maturity shale oil, presenting promising exploration and development prospects. This study delves into the hydrocarbon generation conditions, reservoir characteristics, and oil-bearing property analysis of the mud shale from the Nen-1 and Nen-2 sub-formations of the Nenjiang Formation to pinpoint favorable intervals for shale oil exploration. Through the integration of lithology, pressure, and fracture distribution data in the study area, favorable zones were delineated. The Nen-1 sub-formation is widely distributed in the Changling Depression, with mud shale thickness ranging from 30 to 100 m and a total organic content exceeding 2.0%. Type I kerogen predominated as the source rock, while some samples contained type II kerogen. Organic microcomponents primarily comprised algal bodies, with vitrinite reflectance (R_o) ranging from 0.5% to 0.8%. Compared to Nen-1 shale, Nen-2 shale exhibited less total organic content, kerogen type, and thermal evolution degree, albeit both are conducive to low-maturity shale oil generation. The Nen-1 and Nen-2 sub-formations predominantly consist of clay, quartz, feldspar, calcite, and pyrite minerals, with minor dolomite, siderite, and anhydrite. Hydrocarbons primarily reside in microfractures and micropores, including interlayer micropores, organic matter micropores, intra-cuticle micropores, and intercrystalline microporosity, with interlayer and intra-cuticle micropores being dominant. The free oil content (S₁) in Nen-1 shale ranged from 0.01 mg/g to 5.04 mg/g (average: 1.13 mg/g), while in Nen-2 shale, it ranged from 0.01 mg/g to 3.28 mg/g (average: 0.75 mg/g). The Nen-1 and Nen-2 sub-formations are identified as potential intervals for shale oil exploration. Considering total organic content, oil saturation, vitrinite reflectance, and shale formation thickness in the study area, the favorable zone for low-maturity shale oil generation is primarily situated in the Heidimiao Sub-Depression and its vicinity. The Nen-2 shale-oil-enriched zone is concentrated in the northwest part of the Heidimiao Sub-Depression, while the Nen-1 shale-oil-enriched zone lies in the northeast part. Full article

The ultramafic rock located on the northern slope of Lüliang Mountain in the northwestern region of North Qaidam Orogen is altered to serpentinite. The occurrence of disseminated chromite within the serpentinite holds significant implications for understanding the petrogenesis of the protolith. This work provides strong evidence of a distinct zonal texture in the chromite found in the ultramafic rock, using petrographic microstructure and electron probe composition analysis. The core of the chromite is characterized by high contents of Cr^#, with enrichment in Fe^3+# (Fe³⁺/(Cr + Al + Fe³⁺)) and depletion in Al₂O₃ and TiO₂. The Cr₂O₃ content ranges from 51.64% to 53.72%, while the Cr^# values range from 0.80 to 0.84. The FeO content varies from 24.9% to 27.8%, while the Fe₂O₃ content ranges from 5.19% to 8.74%. The Al₂O₃ content ranges from 6.70% to 9.20%, and the TiO₂ content is below the detection limit (<0.1%). Furthermore, the rocks exhibit Mg^# values ranging from 0.13 to 0.25 and Fe^3+# values ranging from 0.07 to 0.12. The mineral chemistry of the chromite core in the ultramafic rock suggests it to be from an ophiolite. This ophiolite originated from the fore-arc deficit asthenosphere in a supra-subduction zone. The estimated average crystallization temperature and pressure of the chromite are 1306.02 °C and 3.41 GPa, respectively. These values suggest that the chromite formed at a depth of approximately 110 km, which is comparable to that of the asthenosphere. The chromite grains are surrounded by thick rims composed of Cr-rich magnetite characterized by enrichment in Fe^3+# contents and depletions in Cr₂O₃, Al₂O₃, TiO₂, and Cr^#. The FeO content ranges from 28.25% to 31.15%, while the Fe₂O₃ content ranges from 44.94% to 68.92%. The Cr₂O₃ content ranges from 0.18% to 23.59%, and the Al₂O₃ and TiO₂ contents are below the detection limit (<0.1%). Moreover, the rim of the Cr-rich magnetite exhibits Cr^# values ranging from 0.90 to 1.00, Mg^# values ranging from 0.01 to 0.06, and Fe^3+# values ranging from 0.64 to 1.00, indicating late-stage alteration processes. The LA-ICP-MS zircon U-Pb dating of the ultramafic rock yielded an age of 480.6 ± 2.4 Ma (MSWD = 0.46, n = 18), representing the crystallization age of the ultramafic rock. This evidence suggests that the host rock of chromite is an ultramafic cumulate, which is part of the ophiolite suite. It originated from the fore-arc deficit asthenosphere in a supra-subduction zone during the northward subduction of the North Qaidam Ocean in the Ordovician period. Furthermore, clear evidence of Fe-hydrothermal alteration during the post-uplift-denudation stage is observed. Full article

To analyze the impact of volcanic rocks in the Offshore Indus Basin on hydrocarbon reservoir formation, seismic data interpretation, seismic data inversion, and sea–land correlation analysis were carried out. The results show that, longitudinally, volcanic rocks are mainly distributed at the top of the Cretaceous system or at the bottom of the Paleocene, and carbonate rock platforms or reefs of the Paleocene–Eocene are usually developed on them. On the plane, volcanic rocks are mainly distributed on the Saurashtra High in the southeastern part of the basin. In terms of thickness, the volcanic rocks revealed by drilling in Karachi nearshore are about 70 m thick. We conducted sparse spike inversion for acoustic impedance in the volcanic rock area. The results show that the thickness of the Deccan volcanic rocks in the study area is between 250 and 750 m which is thinning from southeast to northwest. Based on sea–land comparison and comprehensive research, the distribution of volcanic rocks in the Indian Fan Offshore Basin played a constructive role in the Mesozoic oil and gas accumulation in the Indus offshore. Therefore, in the Indian Fan Offshore Basin, attention should be paid to finding Mesozoic self-generated and self-stored hydrocarbon reservoirs and Cenozoic lower-generated and upper-stored hydrocarbon reservoirs. Full article